When Bob Sanders was fired Jan. 5 as defensive coordinator of the Green Bay Packers, coach Mike McCarthy quickly went to work to find a replacement.

Mike Nolan and Gregg Williams were brought in back-to-back just three days after Sanders and five of his assistants were dismissed.

Within the next week, both Nolan and Williams were hired as defensive coordinators elsewhere.

Nolan, after meeting with McCarthy on Jan. 8, was hired by the Denver Broncos on Jan. 11 - the same day Josh McDaniels was hired as head coach.

On Jan. 15, Williams agreed to Sean Payton's offer to run the defense of the New Orleans Saints.

On Jan. 19, Dom Capers signed on to become the Packers' defensive coordinator.

It is not known whether McCarthy offered the position to Nolan.

Jim Haslett, the former Saints coach, had the opportunity to take the Packers' job, a source said, but there was a timetable attached. Haslett opted to see if he would be named coach of the St. Louis Rams, and McCarthy moved on. The Rams hired Steve Spanuolo, and Haslett now is coaching in the new United Football League.

Williams told the Journal Sentinel on Jan. 20 at the Senior Bowl in Mobile, Ala., that McCarthy offered him the job, but he turned it down after a family vote.

Williams' youngest son, Chase, is one of the nation's top high school prospects at tight end/linebacker in his junior season and preferred to play in the South.

There also was the issue of Williams wanting to find a coaching position for his oldest son, Blake, which Williams was able to do at his previous stops with the Jacksonville Jaguars and Washington Redskins. Williams said the Packers were open to accommodating that request. Some other teams were not.

It probably also didn't hurt that soon after Williams left New Orleans to interview in Green Bay, Payton went to general manager Mickey Loomis and offered up to $250,000 of his own salary to land Williams.

So in the end, the Broncos got Nolan, Williams went to the Saints and Capers joined the Packers.

After four games - a minuscule sampling, to be sure - it would appear as if the Broncos and Saints were the big winners. Both are off to 4-0 starts thanks in large part to vastly improved defenses.

Under Nolan, the Broncos have gone from having the 29th overall defense in yards in 2008 to second in this season.

The Saints have climbed from 23rd to ninth with Williams at the helm.

But the Packers have improved as well, from 20th to 15th.

Each situation has been unique.

The Broncos were all about change as they, like the Packers, moved from a 4-3 scheme to a 3-4.

"The 4-3 really wasn't here," McDaniels said. "The way they had played, the style and the guys. . . . We just felt like it wasn't like we had a solid 4-3 defensive scheme in terms of our personnel to fit that scheme. In other words, why take a year and do that when it really wasn't in place to begin with, so we just said, 'Hey, just go.'

"Everything from the first few weeks that we got here moving forward, we said we're going in that direction regardless. It might not be perfect, but we're going to get it as close to perfect by the time we start playing games. It was that simple."

The Broncos have eight new starters. Five were veterans brought in via free agency who had previous experience in the 3-4 or a multiple, attacking defense: nose tackle Ronald Fields (San Francisco), end Ryan McBean (Pittsburgh), linebacker Andra Davis (Cleveland), and safeties Renaldo Hill (Miami) and Brian Dawkins (Philadelphia). Denver also added end Vonnie Holliday, who stated his disappointment that the Packers didn't look at him, to bring veteran depth to the line. Robert Ayers, the 18th pick in the draft, also has played a lot at outside linebacker after being an end in college at Tennessee.

"Most of the guys (on the roster) didn't have much experience playing in that (4-3) system," McDaniels said. "We were coming in looking at it and looking at what we had and said, all right, let's go ahead and make the transition, move the guys that were ends in the 4-3, move them out to linebacker and then go ahead and start that process. And everyone we've brought in since then has kind of fit that mold."

The Broncos also have had the benefit of playing two of the worst offenses in the league: Oakland (32nd) and Cleveland (29th). But Dallas (fifth) and Cincinnati (14th) are in the upper half.

The Saints, who used a 4-3, were able to keep the same scheme under Williams but added his attacking style.

New Orleans got a big lift when three key starters returned from injury: ends Charles Grant and Will Smith, and cornerback Tracy Porter.

The Saints also added two players in free agency who fit Williams' scheme: cornerback Jabari Greer and safety Darren Sharper. Sharper, the former Packer and Viking, was named NFC defensive player of the week Tuesday and leads the NFL with five interceptions.

"Sometimes the change is necessary, and unfortunately in our business you can't change out an entire side of the ball. I think Gregg and his staff defensively have done a good job, along with the players, of coming into this season with a new approach," said Payton. "We've added some key players (who) were big off-season acquisitions for us."

The Saints have faced only one offense ranked in the upper half: Philadelphia (15th).

In Green Bay, Capers was forced to transform a stringent 4-3 team into a 3-4. And while the Packers, like the Saints, got three defensive starters back from injury - Nick Barnett, Cullen Jenkins and Atari Bigby - Capers got no help in the personnel department.

The only player brought in with 3-4 experience, safety Anthony Smith, was cut before the start of the season.

And while both Denver and New Orleans felt the need to start their rebuilding effort with veteran safeties in Dawkins and Sharper, the Packers left themselves short at that crucial position.

Not only was Smith jettisoned, but after Bigby got hurt again, third-year pro Aaron Rouse was released and Derrick Martin was forced to start a month after being acquired in a trade. Consistency problems in the back end undoubtedly have forced Capers to alter some of the more aggressive schemes that were present during training camp.

But Capers did, without question, have the most talent to work with. Williams said when he evaluated each of his nine possible destinations - including Denver and New Orleans - for talent already on the roster, the Packers clearly were No. 1.

"From the starters to the reserves, the depth of young talent there was really impressive," Williams said. "That was a big mark in their corner."

But Williams was looking at 4-3 players fitting a 4-3 scheme. Capers had to make those players fit a 3-4 scheme.

While Nolan got a speedster end in Elvis Dumervil (eight sacks this season) to play outside linebacker, Capers had to make the same transition with Aaron Kampman (one sack), who is not as good an all-around athlete.

The Packers have played two above-average offenses: Minnesota (13th) and Cincinnati (14th). Chicago (25th) and St. Louis (30th) have struggled, but the Packers flexed some strength when they held the league's leading rusher, Adrian Peterson, to 55 yards on 25 carries Monday night.

Capers was asked this week if his defense has progressed the way he envisioned.

"You never know, it's hard to speculate," he said. "I know that we've done some good things through four games. We need to do things more consistently. I think we have the capability of doing things more consistently, and that's what I think will enable us to improve. Our goal is to go out and improve every week.

"I looked at the game (Monday) night and our run defense played the best that it's played this year. Our pass defense didn't. So the key is let's try to get both of those on the same page in the same game."

So after four games, it's obvious the Broncos and Saints have vastly improved on defense with the arrivals of Nolan and Williams, respectively. But they also were aided by the acquisitions of key players who had performed in starting roles elsewhere.

The Packers also have made progress, just not as starkly. But there were no personnel adjustments made. Capers had to, in a sense, fit square pegs into round holes.

What is known is that there are 12 games left. The Packers may play better as they get more accustomed to Capers' scheme. Nolan's squad may fall back to earth as the Broncos go through the league's eighth-toughest schedule the rest of the way. And some of the aging Saints veterans may not hold up.

After all, the verdict at the end of the season is the only one that matters.